The Bureau of Labor statistics reports that illnesses due to repeated trauma accounted for 65 percent of the newly reported cases of occupational illnesses and for one in three lost work time illnesses in 2001. Work-related musculoskeletal disorders (WMSDs) continue to cause substantial worker discomfort, disability and loss of productivity. Animal models provide an opportunity to examine tissue effects under controlled experimental conditions. We have used such a model in the rat to study the development of WMSDs and now propose to test the effectiveness of secondary prevention interventions using our model. In this proposed five-year study, we will use qualitative and quantitative histological, immunochemical, molecular and neurophysiological techniques as well as behavioral testing of motor and sensory function to address two specific aims related to secondary prevention interventions in a rat model of WMSD. 1. To determine the effectiveness of an ergonomic work modification in attenuating the acute and chronic inflammatory phases of tissue injury and repair accompanying performance of a highly repetitive, forceful task. Rats performing a high repetition-high force (HRHF) reaching and pulling task regimen will be transferred to a light duty, low repetition-negligible force (LRNF) task regimen beginning at the onset of behavioral evidence of discomfort. They will be examined at later time points and compared to trained controls that do not perform the task regimen and to controls that perform either the HRHF or LRNF task regimen. 2. To determine the effectiveness of anti-inflammatory medication in ameliorating the acute and chronic inflammatory phases of tissue injury and repair accompanying performance of a repetitive, forceful task. Rats performing a HRHF reaching and pulling task regimen will be given therapeutic doses of ibuprofen beginning at the onset of behavioral evidence of discomfort. They will be examined at later time points and compared to trained controls and medicated controls that do not perform the task regimen and to controls that perform the HRHF task regimen.The use of this model to examine the response of injured and inflamed tissues to secondary prevention interventions will make important contributions to occupational health practice, because we will be testing the effectiveness of hypothesis-based treatments on clinically relevant physiological and behavioral phenomena.